The invention relates to a method of setting a plurality of part regions of a desired protected zone, in which a) the positions of a plurality of monitoring units are detected, with each monitoring unit detecting a detection zone; b) a maximum size of each detection zone is determined; c) the desired protected zone is fixed in a graphical user interface; d) the part regions to be monitored by the respective monitoring units are fixed with reference to the positions of the monitoring units, to the maximum size of the detection zones and of the desired protected zone; and e) the part regions are assigned to the respective monitoring units.